Dynamic k-space filling for bolus chase 3D MR digital subtraction angiography

A bolus chase three-dimensional (3D) MR digital subtraction angiography (MRDSA) technique was implemented using dynamic k-space filling. This technique permits rapid 3D arterial imaging of the entire lower extremity at multiple stations using a single intravenous injection. Image acquisition at the first (most proximal) station starts from the edge of k-space and ends in the center of k-space (edge-center order). Image acquisition for middle stations starts from the edge of k-space, arrives at the center of k-space at the middle of data acquisition, and ends at the edge of k-space (edge-center-edge order). Image acquisition for the last station starts from the center of k-space and ends at the edge of k-space (center-edge order). This dynamic k-space filling minimizes contrast dose and motion artifacts. Bolus chase 3D MRDSA was performed on four normal volunteers and three patients using a multiple-phase 3D fast gradient-echo sequence, 25-ml gadolinium dose, and a prototype stepping table. Total bolus chase 3D acquisition time was 46 s. Mask subtraction using both complex and magnitude subtraction was performed. Complex subtraction was found to be necessary for proper delineation of arteries below the aortic bifurcation. Diagnostic results were consistently obtained for all subjects.     

The magnetic resonance Matas test: Feasibility and comparison with the conventional intraarterial balloon test occlusion with SPECT perfusion imaging

PURPOSE: To evaluate a new MR Matas test that uses a form of contrast-enhanced MR angiography (MRA) with temporary manual occlusion of the common carotid artery whose internal carotid artery (ICA) is to be permanently sacrificed. MATERIALS AND METHODS: The MR Matas test was performed on eight patients using an open type MR imager (Signa Profile 0.2 Tesla ver. 7.5, GE-YMS, Tokyo, Japan). Conventional balloon occlusion Matas test and single-photon emission computed tomography (SPECT) of the brain were performed in all cases within a week before or after the MR Matas test. RESULTS: The MR Matas test was successful in all eight patients without any complications. The image quality of the MR Matas test was generally sufficient to confirm cross-flow from the patent side to the occluded side in comparison with selective intraarterial digital subtraction angiography (IADSA) except in one case. CONCLUSION: Brain perfusion information using MR Matas test is comparable to brain SPECT.     

Dural arteriovenous fistula involving the transverse sigmoid sinus after treatment: assessment with magnetic resonance digital subtraction angiography

Introduction The purpose of this study was to evaluate the utility of magnetic resonance digital subtraction angiography (MRDSA) in showing the presence or absence of retrograde venous drainage (RVD) in patients with intracranial dural arteriovenous fistula (DAVF) involving the transverse sigmoid sinus (TSS) after treatment. Methods Of 16 patients with DAVF involving the TSS, 13 underwent digital subtraction angiography (DSA) and MRDSA before and after treatment, and 3 underwent DSA before treatment and DSA and MRDSA after treatment. Five patients underwent these procedures twice after treatment. A total of 21 examinations after treatment were evaluated retrospectively. The presence or absence of DAVF and RVD was decided on the basis of the DSA findings. Two neuroradiologists reviewed the MRDSA findings concerning the presence or absence of DAVF and RVD. Results DSA showed residual DAVF in 9 and residual RVD in 5 of 21 examinations. MRDSA revealed residual DAVF in 8 of 21 examinations. MRDSA did not show residual DAVF in one examination because of a very small (low-flow) residual DAVF without RVD. MRDSA identified residual RVD in 5 of 21 examinations. MRDSA was completely consistent with DSA concerning the presence or absence of residual RVD. Conclusion MRDSA could evaluate the presence or absence of RVD in patients with DAVF involving TSS after treatment. MRDSA may give reliable information as to whether patients with DAVF involving the TSS should undergo additional DSA after treatment.     

Unenhanced ECG-gated fast spin-echo MR digital subtraction angiography (MRDSA) using short echo-spacing three-dimensional sequence of femoral arteries: initial experience

Purpose:

To compare the image qualities of unenhanced electrocardiographically (ECG)‐gated fast spin‐echo magnetic resonance digital subtraction angiography (MRDSA) using a short echo‐spacing three‐dimensional (3D) sequence, known as sampling perfection with application‐optimized contrasts using different flip angle evolutions (SPACE), and the conventional half‐Fourier single‐shot turbo spin‐echo (HASTE) sequence.

Materials and Methods:

Unenhanced ECG‐gated MRDSA using SPACE and HASTE of the femoral arteries were prospectively acquired in 13 healthy volunteers at 1.5 Tesla (T) MRI. Sequential frontal maximum‐intensity‐projection images produced by subtracting each of 10 systolic images from a diastolic image were evaluated quantitatively using paired t‐test and qualitatively by two blinded radiologists using the Mann‐Whitney U‐test.

Results:

Quantitatively, relative contrast against the background, contour sharpness index, and slope of the sequential signal changes of the superficial femoral artery of MRDSA using SPACE were significantly better than those of HASTE (P = 0.005, P = 0.001, and P < 0.0001, respectively). Qualitatively, the overall subjective image quality and sequential appearance changes of MRDSA using SPACE were significantly better than those of HASTE (P < 0.0001 and P < 0.0001, respectively).

Conclusion:

Unenhanced ECG‐gated fast spin‐echo MRDSA using SPACE produces increments in signal intensity, which reflect arterial pulse wave transmission, more clearly than the conventional HASTE sequence. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Time‐resolved three‐dimensional magnetic resonance digital subtraction angiography without contrast material in the brain: Initial investigation

Purpose

To evaluate a novel magnetic resonance (MR) angiography (MRA) of three‐dimensional (3D) MR digital subtraction angiography (MRDSA) without contrast material, which is essentially 3D true steady‐state free precession (SSFP) with selected inversion recovery (IR) pulse using multiple cardiac phase acquisitions with a short increment delay in the assessment of normal cranial arteries, as a feasibility study before clinical use.

Materials and Methods

Serial MRA images using 3D MRDSA without contrast material were acquired from 10 healthy volunteers. Visualization of normal cranial arteries with time‐spatial labeling inversion pulse (Time‐SLIP) MRDSA was qualitatively compared with the conventional MRA method, 3D time‐of‐flight (TOF)‐MRA.

Results

In all volunteers, serial 3D MRDSAs containing hemodynamic information were successfully imaged. The results of visualization of the branches of the cranial arteries with Time‐SLIP MRDSA were comparable to those of 3D TOF‐MRA. The mean scores ± standard deviations for normal cerebral arteries (internal carotid arteries, middle cerebral arteries, anterior cerebral arteries, posterior cerebral arteries, and basilar arteries) were 2.4 ± 0.5, 2.3 ± 0.5, 2.0 ± 0.7, 2.3 ± 0.7, and 2.5 ± 0.7, respectively.

Conclusion

Time‐SLIP 3D MRDSA is a simple method for obtaining hemodynamic information. Although more MR sequence improvement is needed, it can play an important role in assessing cranial arteries without contrast material. J. Magn. Reson. Imaging 2009;30:214–218. © 2009 Wiley‐Liss, Inc.